The invention relates in general to headlights, particularly for use on automotive and other vehicles, of the so-called "sealed-beam" type.
Hermetically sealed vehicular headlights are being manufactured in greater and greater numbers, because they are characterized by trouble-free operation over longer periods of time than is in general the case with headlights of the removable-bulb type. It is known for example to provide a sealed-beam headlight comprised of individual elements, such as a reflector, a diffuser glass and a light source, which are joined together to form a structure which cannot be disassembled, with the interior of the headlight being filled with an inert protective gas, to protect in particular the reflective material of the reflector. Such a headlight can become useless when it develops even a relatively small defect, and must be thereupon replaced by a new unit; nevertheless, these hermetically sealed deadlights are increasingly prevalent, because damaging chemically reactive gases and exhausts and atmospheric moisture is effectively prevented from penetrating into the interior of the headlight. This prevents a decrease of the reflective ability of the reflecting surface of the reflector or even actual rusting of the reflecting surface, and also prevents misting of the interior surface of the diffusing lens, all of which possibilities are very real with the current degree of air pollution.
A headlight of the type in question is already known provided with a diffuser lens connected to the headlight reflector by means of a cementing material, such as glue or putty or hardenable plastic or the like, with the filament-supporting electrodes of the headlight lamp passing through a metal lamp socket in air-tight manner, and with a cap-shaped annular mounting flange on the lamp being welded to the rear edge of the reflector. Other known headlights of this type make use of a lamp provided with an annular groove, with the rear neck portion of the reflector member being retained in such annular groove by means of a cementing material; in an analogous manner, the front rim of the reflector member is received in a groove in the diffuser glass or lens and maintained in position by means of a cementing material. This expedient has the special advantage that the edges of the front rim of the reflector, which are most susceptible to rusting, are embedded in the cementing material and thereby protected.
A further known construction makes use of a glass socket through which pass the electrodes of the headlight lamp, with the glass socket being provided with a metal centering ring, this centering ring being inserted into the rear opening of the reflector. In this way, a glass bulb can be mounted on the centering ring, so that the electrodes with their filaments are encapsulated in the interior of the reflector. This arrangement enables a trouble-free orienting of the lamp filaments with reference to the reflector, without the separate bulb socket which is also provided for the lamp in this construction necessarily playing a part in the focussing adjustment.